A suburban St. Louis teenager is being treated at a hospital after having his leg cut off by a freight train.

Police tell STLtoday.com, the Web site for the St. Louis Post-Dispatch, that the 19-year-old somehow managed to crawl 50 yards for help, flagging down a passing motorist.

The incident happened Thursday afternoon in Webster Groves. Police don't know why the teen was on the train tracks. His leg, some clothing and a skateboard were found about 50 yards from him.

The intersection is marked with flashing-light signals and gate arms. The train's engineer and conductor were not aware anyone was hit, and the train didn't stop.

The victim's name and details of his condition were not released.